Age patterning in the wild chimpanzee gut microbiota

We assessed changes in gut microbial community composition over the chimpanzee life course. Fecal samples were collected from habituated chimpanzees in two wild groups in Kibale National Park, Uganda between July 2015 and December 2018. Studied continuously since 1987, the Kanyawara group was comprised of 49 individuals in 2015 and 55 in 2018. Studied continuously since 1995, the Ngogo group was comprised of 192 individuals in 2015 and 200 in 2018. All chimpanzees were individually recognized, and none were directly provisioned with human foods, although those at Kanyawara occasionally forage from nearby farms. Chimpanzees at both sites are monitored daily by researchers and Ugandan research assistants. While these groups are only separated by 10-15 km, they exhibit important differences: the Ngogo group is considerably larger, with a higher population density, and has a higher concentration of fruiting trees, leading to improved foraging efficiency and higher energy balance.Fresh fecal samples were collected within minutes of deposit. Sterile wooden spatulas were used to scoop feces immediately into 2 ml of RNALater to reach a volume of approximately 4 ml. Samples were shaken, sealed with parafilm, and then stored in a -20 °C solar freezer at the end of the observation day and until shipment to the U.S. We grouped chimpanzees into 6 age classes (young infant: <2yo, infant: 2-5yo, juvenile: >5-10yo, adolescent: >10-15yo, adult: >15-35yo, past-prime adult: >35yo) that roughly correspond to behavioral and reproductive milestones.